yield_from: implementing yield from func() functionality by modifying yield *func() behavior

Usage

require 'yield_from'
class A
	extend YieldFrom
	def rec(n)
		return to_enum(:rec,n) if !block_given?
		return if n<0
		yield n
		yield *rec(n-1)
	end
	yield_from :rec
end
p A.new.rec(5).to_a # => [5, 4, 3, 2, 1, 0]

There are instance method version and local function version.

Motivation

In the above example, similar code was running until Ruby 2.7 .

class A
	def rec(n)
		return to_enum(:rec,n) if !block_given?
		return if n<0
		yield n
		rec(n-1, &proc)
	end
end
p A.new.rec(5).to_a # => [5, 4, 3, 2, 1, 0]

The bare proc got forbidden in Ruby 3.0.

You can see the discussion at https://qiita.com/cielavenir/items/0cc9189f2c40d6047d8b .

Acknowledgement

Learned Ruby decorator from Nakayama R et al. Automatic Translation of Decorators from Python to Ruby, The 77th National Convention of IPSJ, 2015